1. Field of the Invention:
The present invention relates generally to serial radiographic systems and more particular to an apparatus for obtaining a visible radiation image by use of a stimulable phopshor sheet.
2. Discussion of Background:
When certain kinds of phosphors are exposed to radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to a stimulating ray such as visible ray, light is emitted from the phosphor in the pattern of the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
A serial radiographic system adapted especially for using the stimulable phosphor is described in U.S. Pat. No. 4,236,078, entitled, METHOD AND APPARATUS FOR RECORDING AND REPRODUCING A RADIATION IMAGE, issued to Kotera et al. This patent discloses a method and apparatus of radiation image recording and reproducing which employs a radiation image storage panel including a stimulable phosphor for medical diagnosis. The stimulable phosphor is first exposed to a radiation to have a radiation image stored therein and is then scanned with a stimulating ray which causes it to emit light in the pattern of the stored image. The light emitted from the stimulable phosphor upon stimulation thereof is photoelectrically detected and converted to an electric signal which is processed as desired to reproduce a visible image of a quality suitable for viewing and diagnostic purposes.
In the radiation image recording and reproducing method described above, the final visible image may be reproduced in the form of a hard copy or may be displayed on a cathode ray tube. The stimulable phosphor sheet used in this method may take various forms such as panel, drum or the like, which are herein generally referred to as Imaging plated (IP). For reasons of economy, it is desirable that the IP be used repeatedly in many separate radiographic operations, such as 1,000 operations.
The radiographic system utilizing the stimulable phosphor sheets has a source of radiation which directs a radiation beam towards a spot shot apparatus. The spot shot apparatus has separate IP storage magazines for holding exposed and unexposed IPs. A stack of unexposed IPs is stored in a supply magazine. A transport and drive system sequentially transports the unexposed IPs at high speed from the supply magazine to an exposure station in the path of radiation emitted from the radiation source. After exposure, the IPs are transported to, and deposited in, a receiving magazine. The transport and drive system concurrently delivers an unexposed IP to the exposure station and an exposed IP to the receiving magazine.
The supply and the receiving magazines are removable and are light-tight when removed. This permits loading and unloading of the IPs to and from respective magazines at locations remote from the radiographic system.
The receiving magazine is required to protect the exposed IP thoroughly from exposure to light during carrying of the receiving magazine; the phosphor layer of the exposed IP from damage which might occur during carrying of the receiving magazine due to the rattle of the IPs within the closure of the receiving magazine; and to provide a large enough access opening for receiving the exposed IPs of a given size fed from the transport system, which opening is closable in a light-tight fashion by means of a suitable door.
In the past, various proposals for the receiving magazine have been put forth in an effort to satisfy the above requirements. These proposals have not been fully satisfactory and have had a number of inherent disadvantages, including (1) the proposed receiving magazines were not compact; (2) no provision was made for preventing the rattle of IPs within the receiving magazine during carrying, which resulted in abrasion of the stacked IPs and damage to the phosphor layers thereof; and (3) no provision was made for maintaining a light-tight environment surrounding the exposed IPs upon opening of the entrance door extending across the access opening arranged upon the top of the closure of the receiving magazines.